vein


vein
veinal, adj.veinless, adj.veinlike, adj.
/vayn/, n.
1. one of the system of branching vessels or tubes conveying blood from various parts of the body to the heart.
2. (loosely) any blood vessel.
3. one of the riblike thickenings that form the framework of the wing of an insect.
4. one of the strands or bundles of vascular tissue forming the principal framework of a leaf.
5. any body or stratum of ore, coal, etc., clearly separated or defined: a rich vein of coal.
6. a body or mass of igneous rock, deposited mineral, or the like occupying a crevice or fissure in rock; lode.
7. a natural channel or watercourse beneath the surface of the earth.
8. the water running through such a channel.
9. a streak or marking, as of a different shade or color, running through marble, wood, etc.
10. a condition, mood, or temper: a vein of pessimism.
11. a tendency, quality, or strain traceable in character, conduct, writing, etc.; manner or style: to write in a poetic vein.
v.t.
12. to furnish with veins.
13. to mark with lines or streaks suggesting veins.
14. to extend over or through in the manner of veins: Broad new highways vein the countryside.
[1250-1300; ME veine < OF < L vena vein of the body, channel, ore deposit]
Syn. 11. tone, streak, touch, hint, thread.

* * *

Vessel that carries blood to the heart.

Except for the pulmonary veins, veins bear deoxygenated blood from capillaries, which converge into threadlike venules and then veins, finally emptying into the venae cavae (see cardiovascular system; vena cava). Blood moves through veins by contraction of the surrounding muscles. Backflow is prevented by valves in most veins' inner layer (tunica intima), which lacks the elastic membrane lining of arteries. The thin middle layer (tunica media) is mostly collagen fibres, and the thick outer layer (tunica adventitia) is mostly connective tissue. See also circulation; varicose vein.

* * *

      in human physiology, any of the vessels that, with four exceptions, carry oxygen-depleted blood to the right upper chamber (atrium) of the heart. The four exceptions—the pulmonary veins—transport oxygenated blood from the lungs to the left upper chamber of the heart. The oxygen-depleted blood transported by most veins is collected from the networks of microscopic vessels called capillaries by thread-sized veins called venules.

      As in the arteries, the walls of veins have three layers, or coats: an inner layer, or tunica intima; a middle layer, or tunica media; and an outer layer, or tunica adventitia. Each coat has a number of sublayers. The tunica intima differs from the inner layer of an artery: (artery) many veins, particularly in the arms and legs, have valves to prevent backflow of blood, and the elastic membrane lining the artery is absent in the vein, which consists primarily of endothelium and scant connective tissue. The tunica media, which in an artery is composed of muscle and elastic fibres, is thinner in a vein and contains less muscle and elastic tissue, and proportionately more collagen fibres (collagen, a fibrous protein, is the main supporting element in connective tissue). The outer layer (tunica adventitia) consists chiefly of connective tissue and is the thickest layer of the vein. As in arteries, there are tiny vessels called vasa vasorum that supply blood to the walls of the veins and other minute vessels that carry blood away. Veins are more numerous than arteries and have thinner walls owing to lower blood pressure. They tend to parallel the course of arteries. See also artery; capillary.

▪ ore deposit
      in geology, ore body that is disseminated within definite boundaries in unwanted rock or minerals (gangue). The term, as used by geologists, is nearly synonymous with the term lode, as used by miners. There are two distinct types: fissure veins and ladder veins.

      Fissure veins, the earliest described bedrock deposits, occupy one or more fissures; they are tabular, with two dimensions much greater than the third. Fissure veins are formed in two stages, sometimes greatly separated in time; first the fissure is formed, and then it is filled with ore. There are several varieties: simple, with relatively straight, parallel walls; chambered, with irregular, fragmented walls; dilation, or lenticular, with fat lenses in a string or roughly parallel in schists; sheeted, with several distinct, closely spaced, parallel fractures; and composite, with several roughly parallel fissures and connecting diagonals in partially replaced rock.

      Ladder veins are short, rather regularly spaced, roughly parallel fractures that traverse dikes (tabular bodies of igneous rocks) from wall to wall. Their width is restricted to the width of the dike, but they may extend great distances along it. Ladder veins are not as numerous or important as fissure veins.

* * *


Universalium. 2010.

Synonyms:

Look at other dictionaries:

  • vein — [veın] n ↑artery, ↑brain, ↑fatty, ↑tissue, ↑heart, ↑kidney, ↑intestine, ↑intestine2, ↑small, ↑large, ↑liver, ↑lung, ↑muscles, ↑stomach, ↑vein, ↑ …   Dictionary of contemporary English

  • vein´er — vein «vayn», noun, verb. –n. 1. a) one of the blood vessels or tubes that carry the blood to the heart from all parts of the body. b) any blood vessel. 2. the rib of a leaf; one of the strands or bundles of vascular tissue forming the principal… …   Useful english dictionary

  • vein — [ veın ] noun ** 1. ) count; count one of the tubes in your body that carry blood to your heart. A tube that carries blood away from your heart is an artery. a ) one of the tubes that carry liquids through plants or insects 2. ) singular a… …   Usage of the words and phrases in modern English

  • Vein — Vein, n. [OE. veine, F. veine, L. vena.] 1. (Anat.) One of the vessels which carry blood, either venous or arterial, to the heart. See {Artery}, 2. [1913 Webster] 2. (Bot.) One of the similar branches of the framework of a leaf. [1913 Webster] 3 …   The Collaborative International Dictionary of English

  • VEIN — ist ein Klaviertrio des Modern Jazz aus Basel, Schweiz. Die von der Kritik in einer Reihe mit großen Namen genannte[1] Combo wurde 2006 gegründet und hat bereits vier Alben vorgelegt. Inhaltsverzeichnis 1 Geschichte 2 Diskografie 3 …   Deutsch Wikipedia

  • vein — ► NOUN 1) any of the tubes forming part of the circulation system by which blood is conveyed from all parts of the body towards the heart. 2) (in general use) a blood vessel. 3) (in plants) a slender rib running through a leaf, containing… …   English terms dictionary

  • vein — [vān] n. [ME veine < OFr < L vena] 1. a) any blood vessel that carries blood from some part of the body back toward the heart b) loosely any blood vessel: cf. ARTERY, CAPILLARY 2. any of the riblike supports strengthening the membranous… …   English World dictionary

  • vein|y — «VAY nee», adjective, vein|i|er, vein|i|est. 1. a) of, having to do with, or full of veins, especially blood vessels. b) having prominent veins. 2. Geology. c …   Useful english dictionary

  • Vein — Vein, v. t. [imp. & p. p. {Veined}; p. pr. & vb. n. {Veining}.] To form or mark with veins; to fill or cover with veins. Tennyson. [1913 Webster] …   The Collaborative International Dictionary of English

  • vein — c.1300, from O.Fr. veine, from L. vena a blood vessel, also a water course, a vein of metal, a person s natural ability or interest, of unknown origin. The mining sense is attested in English from late 14c. Figurative sense of strain or… …   Etymology dictionary

  • vein — [n1] mood, tone attitude, bent, character, characteristic, complexion, dash, disposition, faculty, fashion, fettle, hint, humor, line, manner, mind, mode, nature, note, spice, spirit, strain, streak, style, suggestion, suspicion, tang, temper,… …   New thesaurus


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.